Stick/Box/RPi/... for in-car use (Analog output)

[MaXX99]

Hi everyone ...

I have a new car on order, delivery in a few months, and have taken the option of Multimedia screens for the second row passengers.
These are just the screens though with analog inputs (composite, RCA, whilte-red-yellow, .... what's in a name ).

Image here : http://goo.gl/90Nr1o

I am looking for two devices to use in the car to watch movies (and if possible play games) to entertain the kids on long trips (5 & 8 years of age).
Power requirements need to be quite low though since these have to run from the 12V cigarette lighter.

My first idea was to run a pair of Raspberry Pi's with RaspBMC and Retropie on them, add a BT and a Wifi adapter, put a small router with an HDD in the trunk and configure them with a PS3 wireless controller. It does require quite some fiddling, setup and troubleshooting in order to get all of this working though ...

Secondly I was thinking of an Ouya + XMBC on it ..; but this doesn't have an analog output ...

Next in line I turn myself to Android devices which could prove great candidates for my intended use, but I am completely lost in the vast amount of devices available ... especially the ones which could tick all the boxes.

All advice and experiences would be greatly appreciated !

[MaXX99]

If I'm not mistaking following boxes have an AV out :

The CS968 comes with a 5V 3A adapter --> Max 15W
The MK902 with a 5V 2.5 adapter --> Max 12.5 W

I do not know how much power can be drawn from a single 12V socket, but I found an adapter which could deliver 2 X 12W (2 x 2.4A), which - I think - could be sufficient to power 2 boxes ? Normally the power adapter should be sized marginally larger than the max power drain ... I hope

http://www.scosche.com/ipad-usb-car-charger-two-port

I also found an even more powerful adapter capable of delivering 6A ...
And it seems like a higher power version with 8A is under way

http://saicoo-tech.com/html/product/view-2342.html